From 96594be65d131fed2aad55187fa291ab8a1d8934 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Emilio=20Cobos=20=C3=81lvarez?= <emilio@crisal.io>
Date: Tue, 11 Jun 2019 17:42:09 +0000
Subject: [PATCH] style: Don't go through all the part names if not there.

This uses the bit added for tracking part attributes in order to avoid doing
wasted work.

Differential Revision: https://phabricator.services.mozilla.com/D32644
---
 components/style/gecko/wrapper.rs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/components/style/gecko/wrapper.rs b/components/style/gecko/wrapper.rs
index aa59df56bde..70eaa552ed5 100644
--- a/components/style/gecko/wrapper.rs
+++ b/components/style/gecko/wrapper.rs
@@ -590,6 +590,9 @@ impl<'le> GeckoElement<'le> {
 
     #[inline(always)]
     fn get_part_attr(&self) -> Option<&structs::nsAttrValue> {
+        if !self.has_part_attr() {
+            return None;
+        }
         snapshot_helpers::find_attr(self.attrs(), &atom!("part"))
     }
 
@@ -623,6 +626,11 @@ impl<'le> GeckoElement<'le> {
         }
     }
 
+    #[inline]
+    fn has_part_attr(&self) -> bool {
+        self.as_node().get_bool_flag(nsINode_BooleanFlag::ElementHasPart)
+    }
+
     #[inline]
     fn may_have_anonymous_children(&self) -> bool {
         self.as_node()